HID lamps employed arc tubes sealed in outer jackets frequently utilize a coating of a luminescent material on the interior surface of the jacket for light enhancement and/or color correction and/or to produce light having a particular color temperature.
It is occassionally necessary, to produce light having a warm color temperature, say 3000.degree. K. to 3300.degree. K., to employ a relatively heavy layer of a luminescent material. By relatively heavy is meant a material weight greater than 0.007 grams per square centimeter (g/cm.sup.2). Generally, luminescent materials for such lamps are applied by an electrostatic deposition process, exemplified by U.S. Pat. No. 3,999,508. Adhesion problems occur, however, when material weights greater than 0.007 g/cm.sup.2 are required.